Knob for a musical instrument



FIG. 1 is a top perspective view of a knob for a musical instrument showing my new claimed design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a back view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a top view thereof; and,

FIG. 8 is a bottom view thereof.

The features shown in broken lines represent the portions of the knob for a musical instrument that form no part of the claimed design. 

CLAIM The ornamental design for a knob for a musical instrument, as shown and described. 